Giuliani said some 2,000 people are expected to attend. He acknowledged it might be difficult for some family members to be at Ground Zero.

"That area, the World Trade Center, is now a burial ground of very, very large proportions," he said. "For some people it is very comforting being there, for others it may not be of comfort."

Earlier in the day, Giuliani threw his support behind Republican mayoral contender and businessman Mike Bloomberg. He said Bloomberg can best guide the city in the wake of the terrorist attacks.

"I think he has an understanding of the economy, he has an understanding of the things that need to be done to continue to make New York City safe," Giuliani said. "I think he is particularly suited for a time when the mayor needs to know about international politics and the world."

Bloomberg also has picked up the endorsement of New York Gov. George Pataki.